Preservation of mithun ( Bos frontalis) semen at refrigeration temperature

Abstract

The objective of the present study was to investigate the possibility of preserving mithun ( Bos frontalis) spermatozoa at refrigeration temperature using tris–egg yolk diluent. Semen samples were collected from four adult mithun bulls through rectal massage method. Good quality semen samples ( n = 30) were preserved at 4 °C using tris–egg yolk diluent for 72 h. Progressive motility, live spermatozoa count and morphological abnormalities were evaluated every 12 h until 72 h of preservation. The colour, consistency and mass activity of fresh semen samples were found to be creamy white, medium and 3+ to 4+ (5+ scale), respectively. The average (mean ± S.E.) volume (ml), pH and spermatozoa concentration (10 6 ml −1) of fresh semen samples were found to be 0.6 ± 0.01, 6.8 ± 0.03 and 425 ± 48, respectively. Progressive motility and live spermatozoa count were found to be less than 30% ( P < 0.01) after 48 h of storage. Head ( P < 0.05), midpiece ( P < 0.05), tail ( P < 0.01) and total ( P < 0.01) abnormalities were found to be increased significantly over the time of storage. It was observed that progressive motility and live spermatozoa count remained above 30% and 40%, respectively, until 36 h of storage. Simultaneously the percentage of morphologically abnormal spermatozoa was found to be significantly low until 36 h of storage. The results indicate that it is possible to preserve mithun spermatozoa at refrigeration temperature in tris–egg yolk diluent, which can be further used for artificial insemination within 36 h of storage.